1. Field of the Invention
The present invention relates to a display device such as a liquid crystal display device and a television receiver having the same, and more specifically relates to a display device having a cooling mechanism arranged to cool electronic or electrical components disposed inside the display device and a television receiver having the same.
2. Description of the Related Art
A generally used translucent liquid crystal display device, which is cited as an example of display devices, includes a liquid crystal panel arranged to display an image and a lamp as a light source disposed behind the liquid crystal panel. Light emitted from the lamp passes through the liquid crystal panel, making an image displayed visible on a front side of the liquid crystal panel.
On a peripheral portion of the liquid crystal panel, TABs on which source driver ICs, gate driver ICs and the like are mounted and a printed circuit board on which other electronic or electrical components are mounted are installed. Each of pixels formed by the source driver ICs and the gate driver ICs on the liquid crystal panel is applied with voltage to control directions of liquid crystal molecules. A control circuit board that controls the source driver ICs and the gate driver ICs is disposed behind the lamp. An inverter circuit board that produces a high volt alternating current which is provided to the lamp is disposed also behind the lamp.
Electronic or electrical components included in the display device, for example, the source driver ICs, the gate driver ICs, and the electronic or electrical components mounted on the control circuit board and the inverter circuit board, generate heat during operation. Especially, the source driver ICs, a control IC mounted on the control circuit board, and a primary side transistor of an inverter circuit mounted on the inverter circuit board generate a large quantity of heat since a large current flows therethrough. In addition, these electronic or electrical components are covered with a metallic cover in view of the necessity of preventing the entry of dust particles from the outside of the display device or preventing the leakage of electromagnetic waves. Thus, the heat generated by the electronic or electrical components is apt to be accumulated thereabout.
In addition, recent increases in the size of the liquid makes the current flowing through the electronic or electrical components larger, thus making the quantity of generated heat larger. In order to maintain intended performance, the electronic or electrical components should be cooled.
As a configuration to cool the electronic or electrical components that generate a large quantity of heat, considered is a configuration to install a cooling element or member such as a radiating fin on the electronic or electrical components. However, in this configuration, the radiating fin should be brought into intimate contact with the electronic or electrical components in order to increase efficiency in cooling, and an excessive force is exerted on the electronic or electrical components. Thus, there is a possibility that the electronic or electrical components are apt to come off the circuit boards or a film.
As a configuration to cool the electronic or electrical components without the installation of the cooling element or member such as a radiating fin, proposed is a configuration to use a cooling fan (see Japanese Patent Application Unexamined Publication No. 2005-25111). In this configuration, the cooling fan is placed in proximity to a horizontal scanning driving circuit unit in order to cool the horizontal scanning driving circuit unit, so that performance deterioration due to the heat generation is prevented.
However, this configuration presents problems as described below. First, an electric motor provided to the cooling fan as a rotation driving source has a lifetime far shorter than the lifetime of the liquid crystal panel or the lamp, which presents a problem in view of the design of the display device. In addition, when the display device provided with the cooling fan is used in a television receiver or the like, a rotation sound made by the electric motor could be sometimes perceived as a noise by the user if the television receiver is used at a low sound level. Such a generation of noise is not preferable in view of the quality of the display device.